Nano-encapsulation, which is one form of nanotechnology, is a method of protecting effective ingredients from the exterior environment and increasing bioavailability. In particular, as nano-carriers, liposomes using natural food ingredients are prepared using phospholipids which are constituent components of the human body.
Liposomes have advantages of having high biocompatibility in the human body, of possibly loading both liposoluble and water-soluble physiologically active substances, increasing permeability of cell membrane phospholipids, and enabling biodegradation in the human body. In addition, liposomes are considered to be highly available as a carrier in drug delivery systems because they can decrease toxicity of loaded drugs and protect active drugs from intrinsic factors such as heat, light and enzymes.
Liposomes are highly available owing to these advantages, but have a drawback of causing chemical decomposition or physical change during manufacture or storage. Chemical decomposition results from oxidation or hydrolysis of phospholipids, and physical change includes agglomeration and cohesion of liposome particles in an aqueous solution, leakage of effective ingredients or the like. Accordingly, there is a need for methods capable of stably storing liposomes while protecting the same from these factors.
One recently actively researched method of powderizing liposomes is lyophilization, which can improve safety of liposomes when stored for a long time.
Lyophilization is a drying method which involves freezing a solution-phase sample and allowing the sample to stand under a reduced pressure to remove moisture from the sample by sublimation and has been variably used for samples containing unstable ingredients including biomaterials. Lyophilization is a method which can improve safety and long-term storage stability of active ingredients and has advantages of easily storing, transferring and handling active ingredients. Lyophilization is applicable to the production of agricultural products, chemicals and various foods such as herbs, and is also utilized to improve safety of liposomes.
Lyophilization is currently used as a method of powderizing liposomes for two reasons. First, since moisture is removed at a low temperature, hydrolysis of phospholipids can be prevented when water is removed from an aqueous liposome solution. Second, since mobility of molecules in a solid phase is decreased, physical and chemical decomposition can be reduced.
Conventionally researched liposome powderization methods can improve storage stability of liposomes, but have drawbacks of low flowability and workability. Accordingly, in order for liposomes to be applied to functional health foods, research on novel formulations that are suitable for the liposomes is needed and powderized nanoliposomes should be dispersed again in water upon ingestion.